The present invention relates to communications between a mobile unit and a general packet radio service (GPRS) gateway support node (GGSN). More particularly, the present invention relates to the employment of session initiation protocol (SIP) for establishing the proper resource reservation protocol RSVP capabilities and requirements as a prerequisite to establishing a communication using RSVP and further establishing quality of service (QoS) capabilities of the UE and GGSN to insure the desired quality of service (QoS).
Currently, the third generation partnership project protocol (3GPP) standards allow for the optional support of resource reservation setup protocol (RSVP) in the user equipment (UE) and in the GGSN as signaling protocol to ensure quality of service. Current standards provide a separation between call setup procedures and establishment of QoS. For example, a UE having RSVP-capability may initiate a call (session) to a non-RSVP capable UE operating in a non-capable RSVP network. The lengthy call establishment procedures will successfully take place but without any indication of the intended protocol to be used for QoS. Upon establishment of the call, the RSVP capable UE will start sending RSVP signaling messages in order to reserve resources that are necessary to carry the media stream along the route to the terminating end. These RSVP messages will be carried across the Internet, only to find a non-capable UE and a non-capable GGSN to complete the reservation procedures. The lack of response from the terminating side to the originator of the RSVP signaling will result in expirations of the resources allocated to this particular media stream at both sides during the call establishment stage, resulting in a dropping of the session and a billing for service that could not have been offered. This inefficient use of system resources reduces overall system capacity and efficiency due to the fact that such a scenario would be persistent in call (session) setups between capable and non-capable RSVP networks and UE. In addition, current technology provides optional support for resource reservation protocol (RSVP) in both user equipment (UE) and universal mobile telecommunication services (UMTS) core network GGSN. As a result, neither the UE nor the GGSN can make any assumptions regarding the support of such protocol except for that it is not applicable, i.e., NA is a default mode of operation. It is therefore important to provide a mechanism to enable an RSVP-capable UE and an RSVP-capable GGSN to inform one another of their RSVP capabilities before any communications can take place using RSVP.